1. Field of the Invention
This invention relates to a method and apparatus for decomposing an organic solution composed of a chelating solution and/or an organic acid containing radioactive metal ions, and further to a method and apparatus for collecting radioactive metals using the same, which are used for removing, or decontaminating, the radioactivity of radioactive metals coming out of atomic power plants and the like.
2. Description of the Related Art
In decomposing waste solutions disposed out of atomic power plants and the like, there have hitherto been raised problems of collecting radioactive metals by way of dissolution. For instance, machinery and equipment installed at an atomic power plant are exposed to and laden with radioactivity and hence are required to be decontaminated by removal of their surface layers. and this poses a problem of collecting the resultant radioactive metals by way of dissolution.
The above problem can generally be coped with by removing the surface layers of the machinery and equipment by sand blasting or the like and by dissolving the resultant metals in an acid or the like to collect them. Here, the term "collect" can be taken as meaning "remove", and in the present invention is used including such meaning. The dissolution and collection steps can be conducted with an inorganic acid, an organic acid or a chelating solution. However, since an inorganic acid is rather dangerous to handle, a chelating solution or an organic acid is, or both are, usually used.
However, a chelating solution or an organic acid to be used for dissolution and collection of radioactive metals has a problem of its post-treatment in view of its mass volume needed for such treatment.
Because metals to be treated are laden with radiactivity, a chelating solution and/or an organic acid having such metals dissolved therein must be stored in safety and will reach a vast amount in quantity. This invites a social problem as to selection of locations at which to store such solution and acid, expansion of the existing locations, etc. A chelating solution or an organic acid containing radioactive metal ions needs to be cemented at the final stage, but all or most of such solution contains carboxyl group (COOH--) which would adversely affect the structural strength of mortar, rendering cement fixation unfeasible. In order to solve this problem, it is necessary to decompose a chelating solution and/or an organic acid in which radioactive metals have been contained, but any suitable method which would allow the decomposition step to be conducted in an efficient manner has not been found. Moreover, because of low ionizing degree, such chelating solution and/or organic acid is difficult to be electrolyzed or made by any similar treatment, leaving such kind of treatment beyond consideration.